FEATURES AND USE OF
DERMATOLOGIC PREPARATIONS
Features
• Among the dosage forms used in the topical treatment of
conditions and diseases of the skin are ointments, creams,
gels, pastes, and plasters.
• In treating skin diseases, the drug in a medicated
application should penetrate and be retained in the skin for
a while.
• Drug penetration into the skin depends on a number of
factors, including:
1. the physicochemical properties of the medicinal substance,
2. the characteristics of the pharmaceutical vehicle,
3. the condition of skin itself. Normal unbroken skin acts as a
natural barrier, limiting both the rate and degree of drug
penetration.
The skin
• The skin is divided histologically into ,
collectively a laminate of barriers
protecting against permeation by external
agents and loss of water from the body:
1. the stratum corneum (the outer layer),
2. the epidermis
3. the dermis
• Blood capillaries and nerve fibers rise
from the subcutaneous fat into the dermis
and up to the epidermis.
• Sebaceous glands, sweat glands, and hair
follicles originating in the dermis and
subcutaneous layers rise to the skin’s
surface.
• The stratum corneum is 10- to 15-μm thick layer
of flat, partially desiccated, dead epidermal cells.
• The stratum corneum is composed of
approximately 40% protein (mainly keratin) and
40% water, with the balance being lipid,
principally as triglycerides, free fatty acids,
cholesterol, and phospholipids.
• On the surface is a film of emulsified material
composed of a complex mixture of sebum, sweat,
and desquamating epidermal cells.
• The stratum corneum, being keratinized tissue,
behaves as a semipermeable artificial membrane,
and drug molecules can penetrate by passive
diffusion.
• The rate of drug movement across this skin layer
depends on the drug concentration in the vehicle, its
aqueous solubility, and the oil–water partition
coefficient between the stratum corneum and the
product’s vehicle .
• Substances with both aqueous and lipid solubility
characteristics are good candidates for diffusion
through the stratum corneum.
• Once through the stratum corneum, drug
molecules may pass through the deeper
epidermal tissues and into the dermis.
• If the drug reaches the vascularized dermal
layer, it becomes available for absorption
into the general circulation (transdermal
delivery systems).
• Hair follicles and gland ducts can provide
entry for drug molecules, but because their
relative surface area is so minute compared to
the total epidermis, they are minor factors in
drug absorption.
• Differences in emollient and occlusive effects and
ease of application and removal between products
is a factor of the base used and product type.
• oleaginous bases provide greater occlusion and
emollient effects than do hydrophilic or waterwashable bases.
• Pastes offer even greater occlusion and are more
effective than ointments at absorbing serous
discharge.
• Creams, usually oil-in-water emulsions, spread more
easily than ointments and are easier to remove.
• Water-soluble bases are non-greasy and are easily
removed.
Use
1. before applying a dermatologic product, the patient
should thoroughly clean the affected area with soap
and water and dry by patting with a soft cloth.
2. In most instances, a thin layer of medication should
be applied to the affected area and spread evenly
using gentle pressure with the fingertips.
3. Typically, about 1 to 3 mg of ointment or cream is
applied per square centimeter of skin.
4. Unless there is a specified need for an occlusive
dressing to protect the area from excessive contact
or contaminants, a bandage should not be used.
examples of treatments appropriate to
disorders of the various skin layers
• Surface treatment:
• mainly by using:
1.a simple cosmetic application,
2.forming a protective layer
3.attacking bacteria and fungi.
• Some examples include protective films, sunscreens,
and barriers that hinder moisture loss and so avert
chapping( prevent cracks ).
• For topical antibiotics, antiseptics and deodorants,
the surface microorganisms are the target.
• Then, effective surface bioavailability requires that
the formulation should release the antimicrobial so it
can penetrate the surface skin fissures and reach the
organisms.
Stratum corneum treatment:
• The main therapies aimed at the horny layer
improve emolliency by raising water content,
or stimulate keratosis with, for example,
salicylic acid.
epidermis and dermis treatment:
• Drug examples include topical steroidal and
nonsteroidal
anti-inflammatory
agents;
corticosteroids may also be used in psoriasis.
• Antibiotics.
• Anaesthetic drugs such as benzocaine.
• antipruritics and antihistamines alleviate itch.
examples of treatments appropriate to
disorders of the various skin layers
• Skin appendage treatment:
• the sweat glands: with antiperspirants such as aluminium or
other metal salts.
• In acne we use topical exfolients such as salicylic acid,
tretinoin (retinoic acid) or isotretinoin, and benzoyl peroxide
and antibiotics such as erythromycin and Clindamycin.
• Depilatories usually contain strontium or barium sulphides, or
thioglycolates;
FEATURES AND USE OF
OPHTHALMIC OINTMENTS
AND GELS
FEATURES
• The major route by which drugs enter the eye is
simple diffusion via the cornea. Lipophilic drugs are
more capable of penetration than hydrophilic
compounds.
• For drugs that are poorly absorbed by the cornea,
the conjunctiva and sclera provide an alternate
route.
FEATURES
• Compared with ophthalmic solutions, ophthalmic ointments
and gels provide extended residence time on the surface of
the eye, increasing the duration of their surface effects and
bioavailability for absorption into the ocular tissues.
• Medicinal agents are added to an ointment base either as a
solution or as a finely micronized powder.
FEATURES
• The ointment base selected for an ophthalmic ointment must:
1. not be irritating to the eye
2. permit the diffusion of the medicinal
substance throughout the secretions bathing the eye.
3.have a softening point close to body temperature, both for
comfort and for drug release.
FEATURES
• Most often, mixtures of white
petrolatum and liquid petrolatum
(mineral oil) are used.
• Sometimes a water-miscible agent such
as lanolin is added.
• A gel base of PEG and mineral oil is also
used; this form permits water and
water-insoluble drugs to be retained
within the base.
FEATURES
• ophthalmic ointments must meet the
USP sterility tests.
• When an antimicrobial preservative is
needed, among those used are
methylparaben (0.05%) and
propylparaben (0.01%) combinations,
phenylmercuric acetate (0.0008%),
chlorobutanol (0.5%), and benzalkonium
chloride (0.008%).
USE
• the hands should be washed and dried thoroughly.
• Then the ointment tube is held between the thumb and
forefinger and the tip placed near the eyelid without
touching it.
• The patient’s head should be tilted back, and with the index
finger of the opposite hand, the lower eyelid of the
affected eye should be gently pulled downward.
• The tip of the ointment tube should be held slightly above
the inside portion of the sack between the
lower eyelid and eyeball.
• Without touching the tip to any part of
the eye, a thin ribbon of ointment,
approximately 0.25 to 0.5 in., should be
placed along the inside of the lower lid.
• The patient should face down and slowly
close the eye for a few seconds.
• Then any excess ointment should be
wiped from the eyelids and lashes with a
clean tissue.
• After use, the ointment must be capped
quickly and tightly.
• The patient should be advised that blurred vision
will occur as the ointment spreads over the eye
and not to be alarmed.
• If the ointment is to be administered only once daily, it is
often preferable to do so at bedtime, when vision impairment
will be inconsequential.
• It is important to emphasize to the patient that ocular
products if handled improperly can become contaminated by
bacteria that cause ocular infections, which may lead to
serious consequences.
• Thus every effort must be made to avoid touching the tip of
the tube to the eye, eyelid, fingertip, or any other surface, and
the ointment should be used by only one person.
FEATURES AND USE OF NASAL
OINTMENTS AND GELS
• Drugs introduced into the nasal passage are primarily for local
effects on the mucous membranes and underlying tissues
(e.g., nasal decongestants).
• However, drug absorption to the general circulation does
occur through the rich blood supply feeding the nasal lining.
• The nasal route of administration is also used for the systemic
absorption of a number of drugs.
FEATURES AND USE OF RECTAL
PREPARATIONS
FEATURES AND USE OF RECTAL
PREPARATIONS
• Ointments, creams, and gels are used for topical application
to the perianal area and for insertion within the anal canal.
• They largely are used to treat local conditions of anorectal
pruritus, inflammation, and the pain and discomfort
associated with hemorrhoids.
• Substances applied rectally may be absorbed by diffusion into
the general circulation via the hemorrhoidal arteries and
accompanying veins in the anal canal. (suppositories)
• The bases used in anorectal ointments and
creams include combinations of PEG 300 and
3350, emulsion cream bases using cetyl alcohol
and cetyl esters wax, and white petrolatum and
mineral oil.
• When antimicrobial preservatives are required,
methylparaben, propylparaben, benzyl alcohol,
and butylated hydroxyanisole are frequently
used.
Rectal ointment with perforated inserter/
applicator tip.
FEATURES AND USE OF VAGINAL
PREPARATIONS
FEATURES AND USE OF VAGINAL
PREPARATIONS
• Topical products are used to treat
vulvovaginal infections, vaginitis, conditions
of endometrial atrophy, and for
contraception with spermatocidal agents.
• Creams with water-washable bases are
preferred to oleaginous ointments.
• Although some preparations are applied
externally to the vulva, most are intended to
be delivered to the vagina by means of
applicator tips that accompany the
products.
Vaginal cream with inserter.